‘Oumuamua is already on its way out of the Solar System, due to reach Jupiter’s orbit in May of this year and Saturn’s in January 2019, but it’s going to continue to tumble long after it leaves our neighbourhood, the researchers said.

But it won’t tumble forever. Eventually, the internal strains and stresses caused by the motion will bring it to a halt.

The team has calculated how long that “eventually” might be for both a rocky asteroid and an icy comet (since we’re not sure which it is), and concluded that, whichever it is, it’s going to be at least a billion years before its tumble stops.

As for when it started tumbling, that’s a bit harder to say, although the researchers believe it most likely happened in ‘Oumuamua’s own solar system.

“It’s hard to know if it was during planet formation or after the planet formation process,” Fraser said.

“Certainly, more collisions happen while planets are growing than afterwards, so that’s a very good guess. But unfortunately we can’t get a high-resolution image of this thing to see what kind of crater is on it that might be attributed to the collision that caused it to start tumbling.”